1. Field of the Invention
The present invention relates to an endoscope, and particularly to an endoscope suitable for performing an operation of exchanging treatment instruments by using a guide wire in an endoscopy and an endoscopic operation of the pancreaticobiliary duct system.
2. Description of the Related Art
In recent years, an endoscopic treatment using an endoscope has been increasingly performed in the treatment of a disease in the digestive tract system and the pancreaticobiliary duct system. The existing treatments of the pancreaticobiliary duct system using an endoscope include a diagnostic treatment of performing endoscopic cholangiography and pancreatography and also a therapeutic treatment of removing a gallstone located in the common bile duct or the like by using a balloon or a grasping treatment instrument.
In performing an endoscopic treatment of a pancreatic duct, a bile duct, a hepatic duct, or the like by using an endoscope, a surgeon usually and commonly inserts the distal end of an insertion portion of the endoscope into a position in the vicinity of the duodenal papilla, and then selectively inserts a treatment instrument, such as a catheter, into the pancreatic duct or the bile duct while using a guide wire as a guide under X-ray illumination.
In such an endoscopy and an endoscopic operation of the pancreaticobiliary duct system, the guide wire is inserted in the treatment instrument, when the treatment instrument, such as a catheter, is inserted into a treatment instrument insertion channel of the endoscope to be used in the observation or treatment of the pancreaticobiliary duct system with the endoscope.
Therefore, the guide wire is moved in conjunction with the movement of the treatment instrument with respect to the endoscope. Thus, to exchange the treatment instrument with another treatment instrument by using the guide wire as a guide while keeping the distal end of the guide wire inserted in the papilla, for example, the guide wire needs to be held within the distal end of the insertion portion to keep the distal end of the guide wire inserted in the papilla.
In light of the above need, there is an endoscope according to a conventional technique, the insertion portion of which includes guide wire fixing means for unlockably locking the guide wire, as disclosed in Japanese Unexamined Patent Application Publication No. 2002-034905, for example.
The endoscope of Japanese Unexamined Patent Application Publication No. 2002-034905 includes an operation portion connected to the proximal end of the insertion portion, and a treatment instrument elevator base provided in the distal end of the insertion portion and operable by the operation of the operation portion. The endoscope is configured such that a top portion of a leading surface of the treatment instrument elevator base is provided with a slit which functions as the guide wire fixing means for making only the guide wire engageable when the guide wire is elevated through the operation of the treatment instrument elevator base by the operation portion.
According to the thus configured endoscope apparatus, in the observation or treatment of the pancreaticobiliary duct system using the endoscope, as the treatment instrument elevator base is elevated, the guide wire is pressed into and engaged with a substantially V-shaped slit (a wire locking groove) provided in a bottom portion of the treatment instrument elevator base due to the reaction force of the guide wire itself inserted in the papilla, and is pressed against a substantially planar upper surface of a rigid distal end body. Thereby, the guide wire is mechanically fixed.
Further, the endoscope provided with the treatment instrument elevator base in the distal end thereof includes an endoscope in which the treatment instrument elevator base is elevated by a drive arm provided inside a side surface of the distal end to prevent such inconvenience as interference of the projected treatment instrument, such as the guide wire, with an elevator wire or the like, as disclosed in Japanese Unexamined Patent Application Publication No. 2005-304586, for example.